You are suppose to be having heat, now. The heater core is just a radiator that radiates heat, there is nothing mechanical or electrical on the core.

Is the blower motor working? Did you try each setting? Do you hear the flaps moving when you switch setting? Did you bleed the systems?



I am really at a lost now!

 

What about trying the built in Climate Control Diagnostics? Does that work on an XJ8? I've got an XJR and used it to show all my valves, switches, etc are working properly.

Check my Shared folder here for everything I have on AC/Heating Diagnostics, etc.

Climate Control Specifically "1998 climate control diagnostics.pdf" Self Test - starting on page 11.

These are NOT my files, I've collected them over the years. I also have many others in my share found in my signature, but these specifically relate to climate control.

PS: MY Heater Core WAS plugged when I got my car. I had to flush it for a LONG time before it opened up and my heat works well now. Also, my Aux Pump was bad. Both fixed for a couple years now and working very well.

 

All - glad to report that a simple flush of my heater core solved my heating problem. Cost.... $5 ! I bought this "flush" kit at Advanced Auto Parts and used one of the connectors that allow to attach water hose. I disconnected both hoses from firewall (to core), one to the auxiliary pump and other to the valve. Flushed, backflushed, and flushed again. A lot of resistance at first, then eventually water came out the other end! Reconnected and bingo! HEAT. OK, to give the full story, I now created another probelm : misfire on Cyl #8. That is indeed the one closest to the "operations" that took place. I will admit a lot of water was splashing around.... guess I soaked something I was not supposed to. Let hope that either drying the area (assuming short?) or a new coil will do the trick. I would love to be able to actually enjoy the cabin heat in coming cold days ahead....

 

Likely water around the Coil #8. I accidentially left my hood open one night (Cannot figure for the life of me how I did that), but it happened to rain that Summer night and the next day, misfire on a couple cylinders. I opened it up and dried them out, and the miss went away immediately.

 

Thanks SuperSport. I was indeed thinking exactly the same and hoping... unfortunately not resolved though. Coil cover showed a little dampness (on the inside) when removed, but generally all didn't look damp/wet anymore (sat for a day and a half before this). Disconnected connector on cyl#8 and went as far as using hair drier.... but test drive this evening = the same problem. Assuming coil is shot at this point and ordered new one. I could of course switch "bad" coil with a good one and see if I get the code on the other cyl to confirm the coil is shot... I recall when I changed all spark plugs some 6 months+ ago that old plugs / coil rubber cover where quite oily. I read on some thread that oil leakage it's that area is common AND can cause coil short. Hmmmm. Might check that too. But again, coincidence too obvious with all the water involved in my heater core flush.... Stay tuned

Brian

 

Almost ashamed to post this reply, but SuperSport was ultimately correct... if only I REMOVED the coil to notice the spark covered in water !! I limited my inspection to the 4pin connector.... DUH! When removed the coil, it was covered in emulsified oil/water gook, and indeed I could see the plug taking a bath. So cleaned out the coil and dried out the spark plug "compartiment", went as far as replacing the spark ($4, what the heck) and The Cat is purrrrring again. Lessons learned : coil cover is NOT water proof, and the coil itself does not seal the "compartiment" where resides the spark plug. Water needs to stay away from that area. Noted. Now enjoying the heat in the cabin during these ~30 degrees days :-)

 

Glad it has worked out -- heat important this times of year.

I'm surprised you had the core problem -- you are past the changeover.. Did your car always have the Jaguar orange/ red installed?

The seals around the coils get a lot of heat - not surprising that they no longer keep out dirt and moisture. These used to be available as replacements when doing the spark plug service.

 

Great News! And, a cheap fix.